Custom Hot Tub – thinking about building one?

Custom Hot Tub

Can I build a Custom Hot Tub?

From personal experience, there is nothing better than getting into your own custom hot tub. You have designed it. You have built it and you get compliments like “did that come as a kit?”. This is when you know you have done an awesome job in building your custom hot tub.

So, to answer the question, yes, you can build your own custom hot tub. In this article, we are going to look at some of the considerations you should be thinking about. Starting a custom hot tub project without a plan is like turning up to a gun fight without a gun.

You simply don’t want to do it!

Why should you build a custom hot tub?

There are a number of reasons you should build a custom hot tub. Some practical, some for vanity – big smilie face! For me, it was a matter of practicality. I wanted a hot tub but there was simply no way that I was going to be able to get one delivered to the location I wanted it.

My garden is too long and has a tight turn so it could not be craned in and it certainly would not go round the corner to the location I wanted. I just had to build my own. Lucky I did as this has now become a business as I help hundreds of people each year build their own tubs now!

In designing and building your own custom hot tub you also get the chance to make it exactly how you want. The exact size, the exact layout. You get to choose all the features you want to add rather than letting someone else do it for the plastic hot tubs.

It is not as difficult as you may think to build a custom hot tub and you will certainly find on this website all the information you could possibly need.

Custom Hot Tub Considerations?

The Location?

If you are lucky enough to have a number of potential locations for your custom hot tub, think about these points. How are you going to fill the tub? Do you have access to a water supply close by or will you just use a garden hose?

When it comes to emptying your hot tub, where is the water going to go? You cant use your chemically treated water on your lawn or plants so you need somewhere for this to go.

You don’t need to empty the tub that often to be honest, so there is no reason you cannot hook up a long hose down your garden and into the main drain. This is what I do.

Power Considerations.

Your hot tub is going to need power and quite a lot of it to be honest. I have a full article on the electrical requirements for a hot tub here, but a ball park for you – you are going to need 40A and 230-240V even if you are in the USA.

Hot tubs don’t run well on 110V so you need to use your split system in your home to up this to 230V. A qualified electrician can do this for you – it is not something I would recommend you do yourself, even if you are a competent DIYer.

Indoor or Outdoor

Most of the custom hot tubs that I design are located outside. This comes with its own challenges as you are going to need to have some form of insulation. Otherwise, as I have found out myself, the running costs get rather high if you are on electric heating.

Indoor isn’t a huge problem. The one thing that I would say about a custom-made hot tub that is inside is that you need to think about ventilation. Hot and moist air that has nowhere to go will cause damp and mould patches over time. You need to consider air flow and potentially some form of dehumidifying for the room. This is especially true if you are looking to put a custom hot tub in a basement. This is proving more and more popular.

What layout are you going for?

I’ve covered on this blog before about the layout for a hot tub. There are some considerations you need to think about. Building a square or rectangular hot tub from blocks is much easier than designing and building a kidney-shaped tub for example.

You need to think not only about the materials you are going to use, but also your own capabilities if you are doing all the work yourself. For me, I would not consider trying to build any curves out of blocks as I know my bricklaying is just not up to it. I found it hard enough building four and a half courses of block for my own square tub!

Water Height and Skimmer or Infinity?

The depth or water height is also something you should think about. Generally, I use a water height of 90cm or 39.5” and this is to the centre of the skimmer. You can of course build it deeper as this is your custom hot tub!

I’ve mentioned a skimmer here, but perhaps you want to look at some form of infinity edge. These are a little more complicated to build but totally possible. The main different is on the plumbing side of things where the water that overflows is collected in a balance tank. Therefore, the water for the jets is pulled from the tank rather than the tub itself. This is what causes the infinity edge and the overflow of water.

How many jets are you going for?

The age-old question. How many jets can I have in my custom hot tub. The answer to this question is really as many as you like. However, if you are going to have more than 16 jets, you are going to need to have multiple pumps in your plumbing layout. The reason that I say 16 jets is the maximum you can have on a single pump is because of the flower required to power the jets.

The jets themselves need 10 GPM of flow each. Therefore, 16 jets, you need 160 GPM of flow being generated from your pump. Taking a mid-range pump, that is not too far away from the tub and does not need to push the water up any considerable height, you will be generating 200 GPM from the pump which will equate to around 160 GPM by the time it gets to the jets.

The more pipe you have, the more friction and the more flow that is lost. We can of course do a proper calculation to work out the exact flow requirements, but this is just a general rule of thumb.

Are you going to have a blower?

To be honest, this should not really be a consideration as yes, you want a blower in your setup. You may have seen on the plastic shell tubs that there are several venturi valves that allow more air to enter the system when they are turned on.

For a block built or concrete poured custom hot tub, you are not going to use venturi to get air in. It is much easier and more effective (in my opinion) to have a blower on your system.

The costs are pretty lower for a blower. Pretty much all the Spa Packs have a connection for one, so for me, it is a no-brainer and you will have a blower on your tub. Also, it is the blower that makes the “bubbly hot tub experience” that we all know and come to love.

How are you going to heat your hot tub?

I’ve written quite an extensive article here on the different heating methods for your hot tub. There are a number of different options and the main contenders are electric, gas/propane or air source heat pumps. They all have their own advantages and disadvantages so I would recommend that you read the article as it covers these in depth.

A quick summary of the options. Electric is the easiest to install but the slowest to heat up your tub. Gas and Propane heat your tub the quickest and Air Source Heat Pumps are the most economical way to heat your custom-built hot tubs. is the

Adding a water feature to a custom hot tub

What about adding a water feature to your custom hot tub? Again, totally possible and not too difficult. When it comes to water features, I do recommend that they are designed on their own plumbing systems and they have their own pumps.

This gives you the maximum level of control over the water feature. The last thing that you want is to not have enough flow on either your jets or your water feature.

Therefore, even if you are only doing a small waterfall or cascade in your custom hot tub, then you should be putting in a lower drain and a small pump, dedicated just for the water feature.

Can I help you with your custom hot tub?

I can certainly help you with your custom hot tub. Getting the design right from the start is key to any successful project and this will be no different.

The key here as I see it is the plumbing layouts and working out exactly how you want it to function.

Everything is possible, we just have to plan and design for it accordingly.

Please do get in touch if you would like my help with the design.

Want to learn how to build your own DIY Hot Tub –

Looking for plans and designs,

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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